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Published on: September 19, 2016
BCGitis and BCGosis: Clinical Spectrum, Immunological Mechanisms, and Risk Management
Qibin Liu1,2, Xiyong Dai1, Shuang Wei1,3
1Wuhan Pulmonary Hospital, Wuhan Institute for Tuberculosis Control, Hubei Province Branch of National Center for Clinical Medicine of Infectious Diseases, Wuhan 430000, China.
Insights
Bacille Calmette-Guérin (BCG) vaccination prevents tuberculosis but can cause rare adverse events in infants with immunodeficiencies. Newborn screening for SCID allows safe BCG deferral, minimizing risks while maintaining TB protection.
Area of Science:
- Immunology
- Vaccinology
- Public Health
Background:
- Bacille Calmette-Guérin (BCG) is the sole licensed tuberculosis vaccine, administered globally to over 100 million neonates annually.
- BCG provides significant protection against severe childhood TB forms like tuberculous meningitis and miliary TB.
- As a live-attenuated vaccine, BCG carries a rare risk of disseminated BCG disease (BCGosis), primarily in infants with severe immunodeficiencies.
Purpose of the Study:
- To synthesize global data on BCG-related complications published since 2010.
- To analyze the impact of vaccine substrain, administration technique, and host immune status on adverse event rates.
- To propose a risk-assessment tool (BCG-RAKE) for safer BCG vaccine deployment.
Main Methods:
- Systematic review and synthesis of global data on BCG complications since 2010.
- Analysis of clinical spectrum, immunopathogenesis, and epidemiology of BCG-related adverse events.
- Development of an evidence-based risk-assessment checklist (BCG-RAKE).
Main Results:
- Universal newborn screening for severe combined immunodeficiency (SCID) using TREC assays enables identification and deferral of high-risk infants.
- This screening strategy virtually eliminates fatal BCGosis.
- Data synthesis highlights factors influencing BCG complication rates, including vaccine substrain and host immunity.
Conclusions:
- Newborn screening for SCID is crucial for preventing fatal BCGosis.
- The proposed BCG-RAKE checklist can aid in safer BCG vaccine administration.
- Balancing TB control benefits with minimizing BCG-related risks is achievable through informed risk assessment.
Abstract:
Bacille Calmette-Guérin (BCG) remains the only licensed vaccine against tuberculosis (TB), administered to >100 million neonates annually. It confers approximately 70-80% protection against tuberculous meningitis and miliary TB in early childhood, under-pinning its continued use in high-burden settings. As a live-attenuated vaccine, however, BCG can rarely cause adverse reactions ranging from self-limited local lesions to life-threatening disseminated BCG disease (BCGosis), which almost exclusively occurs in infants with severe primary or acquired immunodeficiencies such as SCID, MSMD, CGD, or symptomatic HIV infection. Implementation of universal newborn screening for severe combined immunodeficiency (SCID) using the T-cell receptor excision circle (TREC) assay now enables prospective identification and deferral of these high-risk neonates, virtually eliminating fatal BCGosis. Here we synthesize global data published since 2010 on the clinical spectrum, immunopathogenesis, and epidemiology of BCG-related complications, highlighting the impact of vaccine substrain, administration technique, and host immune status on adverse-event rates. On the basis of this evidence, we propose a practical, evidence-based risk-assessment checklist (BCG-RAKE) to support safer vaccine deployment while preserving the substantial TB-control benefits of universal BCG immunization.
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